Such control apparatuses include a control apparatus for reducing vibrations occurring from the drivetrain, which is for example disclosed in Japanese Patent Application Publication No. 2013-90434. In detail, the control apparatus, which is installed in a vehicle, extracts, from a measured electrical angle of a motor as an example of rotary machines, resonant frequency components of the drivetrain of the vehicle. Then, the control apparatus calculates, according to the extracted resonant frequency components, compensation torque for reducing, i.e. compensating, the resonant frequency components. Thereafter, the control apparatus corrects target torque based on the compensation torque, and controls drive of the motor according to the corrected target torque, thus reducing vibrations occurring from the drivetrain.